Common name: European pine shoot moth
Scientific name: Rhyacionia buoliana
Hosts: The European pine shoot moth prefers two- and three-needled pines, especially red (Pinus resinosa), Scots (Pinus sylvestris), mugo (Pinus mugo), and Austrian (Pinus nigra).
It can produce economic damage in nursery or tree farm situations.
In landscapes, it is a sporadic pest that leads to some dieback, but most of the damage is aesthetic.
This non-native insect is found in many Eastern and Midwestern states, as well Washington state and Oregon.
Damage
European pine shoot moth can do extensive damage to young trees under 12 inches tall.
The most serious damage occurs during the spring feeding. New shoots are often weakened, rather than killed, causing growth distortions to trunks and branches. Terminal branches may be killed outright, which will result in denser growth and the production of multiple stems.
By summer, the needles that were mined first have died and turned brown, and wound areas are covered with protective resin-coated webs.
Early damage indicators are yellowing needles near the tips of twigs and small, clear deposits of pitch around new bud clusters.
Repeated infestations may leave trees unsightly.
Life Cycle
The European pine shoot moth overwinters in the larval stage within the buds of pines. In spring, the larvae resume feeding, moving to undamaged buds.
In its mature larval stage, it is a one-half inch brown caterpillar with a black head. In late May or early June, the larvae pupate within pupal cells in the plant tissue. Adults emerge two to three weeks later.
The adult European pine shoot moth is a rusty orange-red moth with irregular, silvery markings on the forewings, plain brown hindwings, and whitish legs.
After emerging, the moths will mate and lay eggs either singly or in small clusters on needles, twigs, or buds during the next several weeks.
Eggs are flat and, at first, yellow in color, turning reddish-brown as they mature. When the eggs hatch, the new larvae immediately begin spinning a protective tent-like web between the needle sheaths and the stems of the current year’s growth.
The larvae begin mining the base of the needles by boring through the needle sheaths. By mid-summer, the larvae have moved on to feed on new buds and construct new webs. At first, the webs appear translucent and glisten, but later they will solidify into yellowish-white masses.
By August, their feeding has stopped and the larvae will overwinter in the buds
Management
Cultural Management
Since the insect hibernates in the injured branch tips, pruning out these areas will destroy the overwintering pupae before they can become active in the spring.
Biological Management
European pine shoot moth has a number of natural enemies, like lady beetles and parasitic wasps, but they do not reduce the population to any significant degree.
Chemical Management
The best time for management with insecticides is when the overwintering larvae first become active in the spring, before they have a chance to tunnel into new, undamaged shoots and buds or construct their water-repellent tents. A second chance for control is late summer when eggs are hatching. Spray the ends of branches thoroughly in late June.
The pesticide information presented in this publication is current with federal and state regulations. The user is responsible for determining that the intended use is consistent with the label of the product being used. The information given here is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement made by The Morton Arboretum.
For more information, contact The Morton Arboretum Plant Clinic at 630-719-2424 or plantclinic@mortonarb.org.